1. May 4, 1915: The Territory of Hawaii created a law that made it illegal to import or own firearms without a license. This was in response to concerns about firearms in the hands of criminals and the potential for violence.

2. May 4, 1942: The Battle of the Coral Sea, which was fought between the Allies (including American and Australian forces) and the Japanese during World War II, began. It was significant because it marked the first time that a Japanese naval advance was stopped.

3. May 4, 1961: The first group of Peace Corps volunteers arrived in Hawaii. This was significant because it marked the beginning of a long relationship between Hawaii and the Peace Corps, which has continued to this day.

4. May 4, 1971: The University of Hawaii at Hilo was established. This was significant because it was the first time that a four-year university had been established on the island of Hawaii, which had previously only had community colleges.

5. May 4, 1979: The Hawaii Volcanoes National Park was designated as a World Heritage Site by the United Nations Educational, Scientific and Cultural Organization (UNESCO). This was significant because it recognized the unique and important geological and ecological features of the park, which is home to two active volcanoes.